【作者】 周密；

【导师】 里佐威；

【作者基本信息】 吉林大学 ， 光学， 2009， 博士

【摘要】 卟啉分子具有独特的物理化学性质,它在光合作用中心模拟、信息存储、气体传感器、显色剂、抗癌药物、非线性光学材料、液晶材料、催化剂材料及功能分子器件等方面有广泛的应用前景。近年来,通过非共价键相互作用形成的卟啉聚集体在功能卟啉材料设计中表现出更为广阔的应用发展前途。我们利用分子光谱方法来研究形成环境对卟啉聚集体形成结构的影响、高压下卟啉聚集体的结构变化规律以及不同取代基团对卟啉聚集体结构随压强响应的影响,得出结论如下:(1)通过挥发10-5M质子化的四苯基卟啉(Tpp)二氯甲烷溶液的方法形成TppJ聚集体,根据在不同酸、溶剂和取代基团条件下形成卟啉聚集体的电子吸收光谱和拉曼光谱,建立了卟啉聚集体分子不同取向模型,该模型很好地解释了实验中的光谱现象,为此类聚集体形成结构的判断提供了一定光谱依据。(2)结合金刚石对顶砧(DAC)和显微共聚焦拉曼光谱技术,测量了四苯基卟啉J聚集体在13GPa内的高压拉曼光谱,得出了规律性的结论:1、卟啉聚集体结构的变化在加压和卸压过程是可逆的;2、在加压过程中,各个拉曼谱带都近线性地向高波数方向移动,没有新峰的出现、谱线劈裂和频移-压强曲线斜率的陡然变化,说明四苯基卟啉J聚集体在13GPa内没有明显的相变发生;3、随压强的增加苯环ψ3 C-C面内伸缩振动的强度增强,表明卟啉分子中苯环与卟吩环的二面角随压强的增加而减小,因而卟啉分子在分子弹簧垫圈方面有潜在的应用前景。本实验也为研究同类卟啉体系中卟吩环与取代芳香环之间的二面角提供了新的方法。(3)测得了四种中位芳香基取代卟啉Tpyp、Tnpp、Tmpp和Tspp J聚集体常压下的紫外-可见吸收光谱、拉曼光谱以及高压下的拉曼光谱。得出了以下规律性结论:1、此类卟啉聚集体在13Gpa内无相变发生。2、高压拉曼光谱的高波数(1010-1600cm-1)和低波数(200-350cm-1)区的斜率远大于中等波数(350-1000cm-1)区。3、芳香环ψ3 C-C面内伸缩振动强度的增强是芳香环与卟吩环之间二面角减小和基态π电子云离域效应共同作用的结果。根据芳香环ψ3 C-C面内伸缩振动强度随压强变化的斜率,得出分子弹簧垫圈的劲度系数可以通过调节取代基团来实现,为将来分子器件方面的应用奠定基础。更多还原

【Abstract】 This thesis described the effects of solvents, substitution and counterion onporphyrin Jaggregations by electronic absorptionand Raman scattering spectroscopy,and a model of orientation change of porphyrin in aggregate was proposed. Usingdiamond anvil cell (DAC) microscopic Raman technique, we reported the in situRaman measurements of Tpp J aggregates under high pressure up to 13 GPa. Andaccording to the spectral phenomena, Tpp J aggregates can be treated as a candidatefor the potential application of pressure-driven molecular spring washers in parallelcombinations. Additionally, the stiffness of molecular washers can be tunable byproperly choice of meso-substitution.This dissertation can be divided into three following parts:(1) UV-Visible absorption spectra of four Tpp aggregates which were formedfromdichloromethane solution were obtained, all the spectra show red-shifted B band,which are the characterof Jaggregates. But the red shift in the absorption spectra ofTpp (H2SO4)-agg is two times larger than that of the other three Tpp aggregates. Atthe same time, Raman spectra of fourporphyrin aggregates were obtained. Comparedto the single band at around 1080cm-1 in otherthree aggregates, double bands can beseen in the Raman spectrum of Tpp (H2SO4)-agg, and then two parallel experimentsincluding the effects of solvent and substitution on the Raman spectra of Tpp (H2SO4)-agg were given. The results showed that the structure of porphyrinaggregates can be affected by nature of titrating acid and solvent and peripheralsubstitution. At last, a stack card model was built and shown in figure 1. Vibronicspectroscopic technique has potential applications in elucidating the orientation ofporphyrins inorganized molecularassemblies.(2) As aprimary parameterof thermodynamic, pressure has relationship with thetotal energy of the compressed substance, and the phase structure and reaction waymay be controlled by changing pressure because the interatomic distance can be reduced during compression. Porphyrin is the pigment of life, and then high pressureinvestigations on porphyrin aggregates can provide more information about themechanismof structure andphase changes.Figure 2 shows the Raman spectra of Tpp J aggregates at ambient and selectedhigh pressures carried outup to 13GPa.From the frequency-pressure relationship, there is a monotonic increase in thefrequency of all Raman modes throughout the compression process, and we have notobserved changes in the spectra including splitting of modes, appearance of newmodes, or sudden changes in the slope of frequency-pressure curve, so no obviousevidence of phase transition can be concluded during the entire compressionprocesses, on the whole, the slopes (dω/dP) at high-(1010-1060 cm-1) and low-frequency (230-330 cm-1) are greater than that in the middle-frequency (380-1000cm-1) region, suggesting that the chemical bond of greater compressibility, which isassociated with the high and low frequency bands, is more sensitive to compression and makes a majorcontribution to the reduction of the volume.It is considered that the coplanarity of the phenyl groups and the mean porphyrinplane could enhance the coupling between porphyrin and phenylπ-systems,whichthen induce some of the phenyl Raman modes of porphyrin systems get stronger. Inour high pressure Raman experiments, as shown in Figure 2, another interestingobservation is the continuing intensity enhancement of phenylψ3 C-C stretchingmode. Unlike other molecular spring driven by chemical interactions, Tpp Jaggregates can be treated as a candidate for the potential application ofpressure-driven molecularwashers inparallel combinations (Figure 3). And due to thestructure of Tpp, each spring washer has four waves equal to the number of phenylsubstitutes. The dihedral angle between porphyrin plane and phenyl groups decreasedwith increasing pressure, and this transformation is completely reversible duringdecompression. Additionally, this method could be used as a suitable tool forinvestigating the continual variation of dihedral angle between the porphyrin ring andmeso-aryl substituents inporphyrin systems.(3) The physicochemical properties of porphyrin compounds can be affect by βand meso-substitution, in this reports, high pressure Raman investigations on fourmeso-substitution porphyrin Jaggregates have been measured and shown in figure 4.Figure 4 High pressure Raman spectra of porphyrin aggregates, A:Tspp, B: Tnpp, C: Tmpp, and D:Tpyp.According to the high pressure spectral phenomena of porphyrin aggregates, wegot the following conclusion:3.1 There is a monotonic increase in the frequency of all Raman modesthroughout the compression process, and we have not observed changes in the spectraincluding splitting of modes, appearance of new modes, or sudden changes in theslope of frequency-pressure curve, so no obvious evidence of phase transition forallthe porphyrin aggregates canbe concluded during the entire compressionprocesses.3.2 Forall the porphyrin aggregates, the slopes (dω/dP) athigh-(1010-1060 cm-1)and low- frequency (230-330 cm-1) are greater than that in the middle-frequency (380-1000 cm-1) region, suggesting that the chemical bond of greatercompressibility,which is associated with the high and low frequency bands, is more sensitive tocompression and makes a majorcontribution to the reduction of the volume.3.3 The intensity ratio of phenylψ3 C-C in-plane stretching andυ2 Cb-Cbstretching mode (which is located at 1575 and 1540 cm-1 under ambient pressurerespectively) exhibitanearlinearly increase during the pressure rise up below 13GPa.And the over all pressure range 0-13GPa can be divided into two domains (0-6 and6-13Gpa) in which linear relationship have been assumed. At different pressureregions, the slope is different, providing more information about the mechanic of theintensity enhancement. Pressure has a strong impact both on the dihedral anglebetween the porphyrin ring and meso-aryl substitute and on theπelectiondelocalization, and both of them can induce the intensity enhancement of aromaticψ3C-C stretching vibration. Theπelectron delocalization is normally occurred underhigh pressure, so under the pressure range from ambient to 6GPa, below 6Gpa,decrease of dihedral angle between the porphyrin ring and meso-aryl substitute playan important role in the intensity enhancement, while above 6GPa,πelectrondelocalization domains. As we have investigated before, the phenomena of thisdihedral angle decrease make Tpp J aggregates a good candidate for the potentialapplication in molecular spring washer, within the first pressure range, the slope ofthe intensity ratio of aromatcψ3 C-C in-plane stretching toυ2 Cb-Cb stretching modeforTspp, Tnpp, Tpp, Tmpp, and Tpypp self-assembles are 0.151, 0.128, 0.081, 0.053and 0.042 respectively, indicating that the stiffness of molecular spring washers canbe tunable by properly choice of meso-substitution.更多还原